The present invention is generally related to an axial-flow fan device for cooling an electronic device.
As a general rule an axial-flow fan device is employed in cooling an electronic device such as a power supply or a central processing unit (CPU). Typically, an axial-flow fan device is constituted by fan blades attached to an annular impeller and is mounted in a fan frame. The axial-flow fan is operated by generating a control signal in the form of a square wave to alter the magnetic field of the stator of the axial-flow fan, and further the alteration of the magnetic field of the stator will mutually act on the annular impeller so as to drive the fan blades to rotate.
FIGS. 1(a) through 1(c) shows the side view, the rear-end view, and the top view of an axial-flow fan according to the prior art. Four ribs 111 arranged on the fan frame 11 are used to support the bottom plate 112 in which the stator is disposed. The fan blades are surrounded with the fan frame segment 113 as shown in FIG. 1(b). The gaps between the ribs form a large vent for enabling the airflow to flow in/out the fan. While the fan blades are rotating, the cooling air will flow in the fan through an intake opening and flow out of the fan through an outlet opening so as to dissipate the heat out of the electronic device.
Nonetheless, there are several disadvantages in the axial-flow fan of the prior art. One is that the fan frame segment 113 surrounding the fan blades will obstruct the airflow and make the intake opening and the outlet opening narrow and small. Therefore, the air capacity for heat-dissipation is reduced and the heat-dissipating effect is not well accordingly. Furthermore, if the fan blades are thin and long, the fan blades will become frangible.
Consequently, it is desirable to modify the conventional axial-flow fan to increase the air capacity for heat-dissipation and reinforce the fan blades.
It is an object of the present invention to provide an axial-flow fan with an increased air capacity.
It is another object of the present invention to provide an axial-flow fan having reinforced fan blades.
A preferred embodiment of the present invention is an axial-flow fan for cooling an electronic device, including: a fan frame having an intake opening and an outlet opening, an impelling apparatus mounted in the fan frame and having a fan blade and an air gap generation member thoroughly surrounding the fan blade, wherein the air gap generation member is connected to the end of the fan blade for generating an air gap when the fan blade rotates.
In accordance with a preferred embodiment of the present invention, the fan blade is free from being surrounded with the fan frame.
In accordance with a preferred embodiment of the preset invention, the impelling apparatus further includes an impeller for the fan blade to be attached thereon and a blade wheel for the air gap generation member to be mounted thereon.
Preferably, the air gap generation member is made of a plurality of rings parallel to the surface of the fan frame, each of which overlaps and separates each other so as to form the air gap. Optionally, the rings may be discontinuous.
The air gap generation member can be alternatively made of a plurality of sloped structures nonparallel to the surface of the fan frame, for example, spirals.
Another preferred embodiment of the present invention is an axial-flow fan cooling an electronic device, including: a fan frame having an intake opening and an outlet opening, an impelling apparatus mounted in the fan frame and having a fan blade and an air gap generation member partially surrounding the fan blade, wherein the air gap generation member is connected to the end of the fan blade for generating an air gap when the fan blade rotates.
The fan blade is free from being surrounded with the fan frame and the fan frame is arranged on the side of the air gap generation member. Alternatively, a portion of the fan blade is surrounded with the fan frame.
Moreover, the impelling apparatus further includes an impeller for the fan blade to be attached thereon and a blade wheel for the air gap generation member to be mounted thereon.
Preferably, the air gap generation member is made of a plurality of rings parallel to the surface of the fan frame, each of which overlaps and separates each other so as to form the air gap. Optionally, the rings may be discontinuous.
An alternative design of the air gap generation member can be made of a plurality of sloped structures nonparallel to the surface of the fan frame, for example, spirals.
Now the foregoing and other features of the present invention may best be understood through the following descriptions with reference to the accompanying drawings, in which: